1. Field of the Invention
The present invention relates to a data processing method and a data processor utilized in image information processing apparatuses, such as a television receptor, a video camera recorder, a computer and a facsimile.
2. Related Background Art
In recent years, multimedia equipments have been developed actively in company with the progress of personal computers, liquid crystal display devices and communication techniques. One of factors in that the input of image information has been made possible is compression/expansion technique for image data.
With moving picture image compression processing, MPEG2 (Moving Picture Image Coding Experts Group Phase 2) is currently being promoted for its standardization, being featured by time directional redundancy reduction according to movement compensation, compression of space redundancy according to DCT (Discrete Cosine Transform) and coding quantity compression according to Huffman coding (variable length coding), but it needs an enormous processing quantity in movement vector detection processing especially necessary for the movement compensation.
Hereinbelow, a conventional movement vector detecting method (block matching method) will be described in brief.
FIG. 1 is a diagram illustrating a block matching method. In FIG. 1, a frame image 700 at time t1 is called a preceding frame image and another frame image 701 at time t2 is called a current frame due to the relationship of t1&lt;t2.
In the block matching method, the current frame image 701 is divided into small block units and investigated in each block unit to select an image block correlative with the preceding frame image most strongly.
A standard image block 703 is selected from the current frame image 701 and it is defined by about 16.times.16 pixels, for example, in MPED2 etc. The image block showing the closest correlation with the preceding frame image 700 is obtained from a correlational arithmetic operation in an investigation area 704 designated inside the preceding frame image 700.
As a result of the correlational arithmetic operation, assuming that an image block 705 correlative with the standard image block 703 most strongly was detected in the investigation area 704 defined inside the preceding frame image 700. In this case, a difference in spatial position between the image block 705 and the standard image block 703 is calculated to determine a movement vector 706.
The block matching method mentioned above calculates a difference error between unit pixels and accumulates the entire error existing inside a predetermined investigation area to memorize the accumulated error as a correlation error value of the above investigation area. Then, the method investigates the highest correlational block in comparison with correlation error values of other investigation areas to calculate the movement vector from the positional relation with the preceding frame.
Thus, the block matching method is based on the difference error between the unit pixels so that the method has needed an enormous quantity of the arithmetic operation in the movement vector detection.
For example, in case of NTSC signal according to the current television broadcast, if the standard block is defined by 16.times.16 pixels and the search range is .+-.16 pixels, the arithmetic operation quantity is about 20 Mbps. Also, in case of a movement vector corresponding to a larger movement, e.g., of .+-.100 pixels, the processing ability exceeds several Tbps and this makes it difficult to be processed in one chip LSI even though a parallel processing technique is used. Accordingly, the realization of a low-cost LSI has been impossible.
Such an image processing, e.g., a tracking processing of a high-speed moving body, is particularly required to enlarge its investigation area and this has caused an error detection due to a delay in the arithmetic operation processing.